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Monthly Archives: February 2013

Forest fires have been the dominant disturbance regimes in boreal forests since the last Ice Age. Fire is the primary process which organizes the physical and biological attributes of the boreal biome and influences energy flows and biogeochemical cycles, particularly the carbon and nitrogen cycle. Forest fire activity is expected to increase significantly with changing climate, acting as a catalyst to a wide range of ecosystem processes controlling carbon storage in boreal forests. We compared the initial recovery of carbon (C) and nitrogen (N) pools and dynamics following fire disturbance in Scots pine (Pinus sylvesteris) stands in the boreal forests of eastern Lapland (Värriö Strict Nature Reserve), Finland, by sampling soils and measuring soil respiration from sample plots established in a chronosequence of different forest sites with 4 age classes, ranging from 2 years to 150 years after fire disturbance (2, 40, 60, 150 years after fire). The sites are situated north of the Arctic Circle, near to the northern timberline at an average of 300 m altitude.

Our preliminary results show that forest fire has a substantial effect on the C and N pool in the litter layer decaying forest top soil layer, but not in the humus layer and in mineral soil layers. Soil respiration and biomass development showed similar chronological response to the time since the forest fire indicating that substantial proportion of the respiration was originating from the very top of the soil.

Jukka Pumpanen and Frank BerningerDepartment of Forest Ecology
University of Helsinki

Map of sulphur depositions for the study sites in 1980. Adopted from Savva & Berninger (2010).

Human activity has altered climate, atmospheric carbon dioxide concentrations, and the concentrations of several pollutants over the last few decades. At the same time, short‐term reactions of tree growth to climatic variations have changed during the last few decades, for reasons that are poorly understood. However, the effects of the pollutants on growth of boreal forests in these remote areas have not been quantified, but even small changes in the productivity of boreal forest should have a large effect on the carbon balance.

The growth of Scots pine, the most important forest species in boreal Eurasia, has declined by about 17% or 0.0025 mm per year from the 1930s to the 1980s in northern Eurasia. We determined this by analysing 40 tree ring chronologies north of 60°N latitude and and factoring out the age and climate effects. Although the study sites were previously considered low‐pollution pristine environments, the growth decrease was significantly related to sulphur depositions. Additionally, we observed that the sulphur depositions rendered the Scots pine forests more sensitive to drought. Although the negative effects of local pollution on plant growth have been widely observed in the past, the long-term effects of sulphur emissions and its spread to ecosystems distant from the sources of pollution have never been previously documented at such a large scale.

These results are of fundamental importance for attempts to preserve the functioning of these forest ecosystems: sulphur deposition rates are still increasing in several regions of the world including the forested boreal areas of north-eastern China and eastern Russia. On the other hand, according to the European Monitoring and Evaluation Programme (EMEP) model, sulphur deposition at 35 sites in boreal Eurasia has been decreasing with a rate ranging from 0.25 to 2.92 kg S ha-1 per every 5 years over the period 1980 to 2000. This decrease in sulphur deposition should slow down the growth decline in boreal Eurasia, but the rate of growth decline will depend upon the ability of trees to recover from sulphur deposition effects, and combination of other environmental factors, such as the frequency of droughts.

The FCoE has had a major input in land-atmosphere research on many levels and in various disciplines, such as the exchange of trace gases and aerosol particles between forests/lakes/wetlands and the atmosphere, micrometeorology, theoretical and empirical aerosol dynamics, and observations and modelling of all these in many different climatic zones from the tropics to the Arctic.

However, the effect of the FCoE does not end there; the research conducted in Kumpula and in Viikki contributes significantly to socioeconomic issues related to global sustainability and land-atmosphere-society interactions as well. Research programmes such as PEEX (Pan-Eurasian EXperiment), iLEAPS (Integrated Land-Ecosystems – Atmosphere Processes Study), and HENVI Forests and Climate Change concentrate on the effects of climate change on the environment and agriculture, forestry, energy consumption, urban planning, and extreme events. The FCoE is equipped to deal especially with questions such as sustainable managed environments and the mixed anthropogenic (sulphur and nitrogen) and biogenic (BVOCs) input to cloud and aerosol processes. The FCoE research is applied to socioeconomic issues also via the National Climate Panel chaired by Prof Kulmala; via the FCoE’s membership of the Forum of Environmental Information that produces scientific information for policy-making; and via Future Earth, the international initiative on global sustainability led by ICSU, ISSC, and UN. Yet another new avenue is opening this year, when the FCoE begins to steer the Finnish global change research towards global sustainability science co-designed by funders, scientists, and policy-makers: Prof Markku Kulmala has been elected to chair the new Finnish Global Change National Committee that will lead this development; Tanja Suni is also involved in the Committee as a Global Environmental Change programme expert.

As a major player in all these organisations, the FCoE will add value to the research conducted by its members also by advancing major global observation infrastructures such as the SMEAR and ICOS networks where the FCoE has a leading coordinative and research role; finally, the uniquely multidisciplinary composition of the group also allows a systems approach to land-atmosphere interactions from soil to vegetation and to atmospheric chemistry and cloud processes.

Today, more than half of world’s population resides in urban areas, and this fraction is

View off the roof top of Dynamicum showing the SMEAR III measuring tower. Photo: Antti-Jussi Kieloaho.

further expected to increase rapidly in the next decades. Thus, a growing number of people will be affected by urban climate. The ability to understand the processes leading to this specific micro-climate is crucial for sustainable urban planning and our quality of life.

In our Centre of Excellence, the Micrometeorology group has been observing the interactions between urban surface and the above atmosphere at the urban measurement station SMEAR III (Station for Measuring Ecosystem Atmosphere Relations) since 2005. We measure the vertical exchange of energy, water, carbon dioxide and aerosol particles with the state-of-the-art methodology, the eddy covariance technique, at two locations: on a measurement mast in semi-urban Kumpula and in downtown Helsinki on top of Hotel Torni. In addition to these continuous measurements, our group also conducts short-term campaigns to observe the land-atmosphere exchange of N2O and volatile organic compounds (VOC) in this urban micro-climate.

The aim of these measurements is to collect long time series of simultaneously measured exchange processes to develop parameterizations for various atmospheric models, and to understand the processes and their changes in time. We are interested how the different urban land use types, particularly green areas, affect the vertical exchange of different variables. For example, as a rough estimate for carbon dioxide, Annika Nordbo, Leena Järvi, Sami Haapanala, Curtis Wood and Timo Vesala recently found that if natural areas cover over 80% of the urban surface, the uptake of vegetation exceeds the carbon dioxide emissions in the source area (Nordbo et al. 2012). Thus, our measurements provide information for urban planners as well as evaluation data for air quality, numerical weather forecast and climate models.

The measurements are also part of the new Urban Boundary-layer Atmosphere Network (UrBAN) which combines a variety of different instrumentation providing data of the interaction between an urban surface and the atmosphere at different spatial scales. The network is a joint effort by the Finnish Meteorological Institute and the Division of Atmospheric Sciences. We also collaborate with groups around the world working with urban flux measurements. The near future plan is to compare the turbulent energy balance fluxes from Beijing and Helsinki using both measurements and modelling approaches.

IIASA is located in the Laxenburg Castle, former summer retreat of the Habsburgs imperial family outside Vienna, Austria.

One of the largest challenges in search for solutions for problems concerning climate, environment, or poverty, is to generate a fruitful communication between scientists and policy makers. Currently, I work in the MAG group (Mitigation of Air Pollution & Greenhouse Gases) at IIASA (International Institute for Applied Systems Analysis), an institute specialising in this communication. How does this communication work? And why is IIASA heard (or is it)? In the following I list a few (possible) reasons for the important role IIASA has in the international policy arena. Note that these thoughts are mine, and they are based on my experiences only.

– History and tradition. IIASA was founded in the middle of the Cold War, in 1972, on the initiative of US president Lyndon Johnson and USSR premier Aleksei Kosygin (the era and the participants may explain the obscure name of the institute). The goal of IIASA was to promote co-operation between East and West in interdisciplinary scientific problems too wide for national institutions to handle. After the Cold War, the co-operation was extended from the East-West axis towards global, now crossing the boundaries between the first and third world. This background gives IIASA a strong label of neutrality. As a result of this history, IIASA scientists visit Brussels regularly to report our results to EU decision-makers. Similarly, representatives of the EU member countries regularly visit IIASA to update their information on, for example, the countries’ energy production and consumption, industry, transport, related technological objectives and future development.

– Continuous funding. More than half of IIASA funding comes from the NMOs (National Member Organizations, Finnish representative being the Academy of Finland), which typically receive most of their funding from the governments they represent. There are currently 20 NMOs, from all the continents, including the most important players (USA, Russia, China, India, Brazil, Germany, Japan, Australia). Of course, there are also NMOs that have stopped their contribution for supporting IIASA, but the typically five year long contracts are, I guess, relatively stable under the current economics.

– Policy-friendliness. IIASA transforms its scientific results into dollars/euros and human lives. The main output of the MAG program, the GAINS emission model, for example, gives out not only the efficiency of the technologies for decreasing emissions, but also their price. Furthermore, it estimates how many human lives can be saved by paying that price. And even further, it can be set to optimize the abatements of different emissions (different in sources and pollutants) in order to achieve the maximal benefit for a certain cost. And the data is available to anyone, registration as a user is free of charge. Another example would be the ‘7 shocks and Finland’ –project, ended a year ago, which analysed how the Finnish national economy would survive the economic shock situations.

These organisations are necessary because the purely academic results that universities provide are often too exact or theoretical for basing political decisions on. Thus, in order to have political influence, I find researchers and other well informed agents should, firstly, support (by actively offering information and, possibly, some resources) institutions such as IIASA, SYKE, the Climate Panel and the Forum for Environmental Information which are currently responsible for refining the scientific results to a form applicable to policy. Secondly, already at university level, we should put effort in offering simplified enough versions of our results to the media and thus to have also the non-academic people to hear and understand them: if the journalists do not understand the press-releases, the results never reach the news.

Most importantly, both above points must be carried out continuously, even if results are not immediately observable: at that very moment when the majority of decision makers feel that change is necessary (and voters are ready for it), we should be able to offer updated and comprehensive knowledge on feasible options, on their effectiveness and price. I guess very few of the reports by IIASA lead to immediate decisions, but when some decisions suddenly are to be made, it is too late to start scanning through ACP, JGR or BER and discussing what could be suggested for an action.

A new book, Physical and Physiological Forest Ecology, is now available from Springer. The editors are Prof. Pertti Hari, Prof. Kari Heliövaara, and Dr. Liisa Kulmala.

This important contribution is the result of decades of theoretical thinking and high-value data collection by the University of Helsinki examining forest ecosystems in great detail. The ecology is dominated by a qualitative approach, such as species and vegetation zones, but in contrast quantitative thinking is characteristic in the exact sciences of physics and physiology. The editors have bridged the gap between ecology and the exact sciences with an interdisciplinary and quantitative approach. This book recognises this discrepancy as a hindrance to fruitful knowledge flow between the disciplines, and that physical and physiological knowledge has been omitted from forest ecology to a great extent. Starting with the importance of mass and energy flows in the interactions between forest ecosystems and their environment, the editors and authors offer a strong contribution to the pioneer H. T. Odum and his work from over 50 years ago.

This book introduces a holistic synthesis of carbon and nitrogen fluxes in forest ecosystems from cell to stand level during the lifetime of trees. Establishing that metabolism and physical phenomena give rise to concentration, pressure and temperature differences that generate the material and energy fluxes between living organisms and their environment. The editors and authors utilize physiological, physical and anatomical background information to formulate theoretical ideas dealing with the effects of the environment and the state of enzymes, membrane pumps and pigments on metabolism. The emergent properties play an important role in the transitions from detailed to more aggregate levels in the ecosystem. Conservation of mass and energy allow the construction of dynamic models of carbon and nitrogen fluxes and pools at various levels in the hierarchy of forest ecosystems.

Testing the predictions of these theories dealing with different phenomena in forest ecosystems was completed using the versatile and extensive data measured at SMEAR I and II (Stations for Measuring Ecosystem Atmosphere Relations) and at six additional stands in Finland, and five stands in Estonia. The theories are able to predict fluxes at different levels in the forest ecosystem gaining strong corroboration in the numerous field tests. Finally, the combined results from different hierarchical levels in the forest ecosystem form the physical and physiological theory of forest ecology.

iLEAPS Executive Officer Tanja Suni and iLEAPS-Eurasia Executive Officer Hanna Lappalainen travelled to the 3rd International Symposium of Arctic Research (ISAR-3) in mid-January with the aim to create new collaboration between iLEAPS, iLEAPS-Eurasia, and Japanese and Russian scientists. One of the main points of collaboration was the Pan-Eurasian Experiment (PEEX), a new iLEAPS project coordinated by iLEAPS-Eurasia at the Division of Atmospheric Sciences in the University of Helsinki. The Finnish delegation also included Joni Kujansuu, the Finland-Asia coordinator of the Division working part-time for iLEAPS.

The delegation met five members of the Science Committee of iLEAPS-Japan in a small satellite meeting on the second evening of the conference. All the Japanese researchers present at the meeting are leading scientists in fields very relevant to either the new iLEAPS theme Sustainable Managed Ecosystems or to the Pan-Eurasian Experiment or both; Drs Takeshi Ohta, Tetsuya Hiyama, and Ayumi Kotani have more than 15 years of experience with land-atmosphere-society interactions in Eastern Siberia (http://www.chikyu.ac.jp/rihn_e/project/C-07.html) whereas Dr Kentaro Hayashi leads a large manipulation experiment on Japanese rice paddies at the Tsukuba University, looking at the influence of CO2 enrichment on carbon, methane, and, uniquely in Japan, also on reactive nitrogen cycles throughout the year (Free Air CO2 Enrichment experiment FACE http://www.niaes.affrc.go.jp/outline/face/; with nitrogen, FACE-N). The website of iLEAPS-Japan is now available in English as well; this will enable European scientists to keep track of the many land-atmosphere research activities in Japan especially around ASIAFLUX, where the leader of iLEAPS-Japan, iLEAPS SSC member Dr Nobuko Saigusa and iLEAPS-Japan coordinator Sawako Tanaka work actively to widen the flux measurement network in Japan, Korea, and other parts of South-East Asia. iLEAPS-Japan and coordinator Joni Kujansuu will also conduct enquiries in the Philippines in order to organise regional land-atmosphere-society activities there; one of the first steps will be an iLEAPS-ASIAFLUX early-career scientist workshop planned to take place in the Philippines in 2014.

iLEAPS IPO and iLEAPS-Eurasia would like to extend a very warm thank you for the entire iLEAPS-Japan group for a very pleasant and fruitful meeting!